TOKYO — On the outside, Toyota’s redesigned Mirai hydrogen fuel cell sedan gets a sleek and sexy, top-to-bottom makeover. But the real revolution is what happened under the skin.
The reengineered fuel cell stack is more refined, and it will be the building block for a variety of hydrogen-powered products Toyota will roll out — beyond the new Mirai.
Toyota Motor Corp. is one of just a handful of global automakers now seriously pursuing hydrogen fuel cell technology and wants its new stack to power a range of trucks as the automaker expands fuel cell use to trains, ships and stationary power generators for industrial use.
Toyota debuted the new stack technology this month in the second-generation Mirai. But the unveiling was part of a flurry of announcements that Toyota insiders called “Fuel Cell Week.” Among the news was word that Toyota will use the Mirai’s fuel cell system — with two stacks instead of one — in a set of Class 8 heavy-duty semitrucks being prepared for trial runs at the Ports of Los Angeles and Long Beach.
Toyota also said trials will take place next year in Japan for light-duty trucks.
The product plans came to light after Toyota kicked off the creation of the Japan Hydrogen Association, a new organization that will promote the formation of a hydrogen supply chain. Other members include Toshiba Corp., banking giant Sumitomo Mitsui Financial Group, Kawasaki Heavy Industries and Japanese energy companies Eneos, Iwatani and Kansai Electric.
Toyota is so confident in future demand for the technology that it ramped up fuel cell production capacity to 30,000 units a year, a tenfold increase over its previous-generation stack.
“With the first generation, we learned that there was more need for commercial use than we thought,” Masahiko Maeda, president of Toyota’s Powertrain Co., said at a Mirai test drive event here. “Since there are so many different needs — forklifts, buses, moon rovers, trucks, trains, ships, generators — we need to have the capacity to supply not just stacks for Mirai, but enough capacity to supply all the others. It is good to spread hydrogen in various ways.”
The first-generation Mirai, which debuted in Japan in 2014, notched just 11,365 global sales in nearly six years through October. Finding new applications and cutting costs is key to building on this meager start.
The new stack makes several improvements over the old one.
Not only is the new stack smaller and lighter, it achieves an output density of 5.4 kilowatts per liter, compared with 3.5 kW per liter in the old. And crucially, the new stack is much less costly.
Engineers slashed the cost of producing the stack some 70 percent, Deputy Chief Engineer Ryotaro Shimizu said. This was done by reducing the number of cells to 330 from 370 and cutting the amount of precious metals used. The amount of platinum was cut 58 percent.
Additional savings came from a reduction in the cycle time required to make the cells, and by shaving two-thirds off the time needed to wrap the hydrogen fuel tanks in costly carbon fiber. Further gains will come from spreading the use of the stack to other vehicles.
Toyota is making the fuel cell stacks at it Honsha plant in Toyota City, but the Mirai has been added to mixed production on the same line as the Crown sedan at the Motomachi plant, eking further production synergies.
The Mirai’s driving range also has increased by about 30 percent. That comes partly from adding a third hydrogen tank and partly through improved efficiencies in the new hydrogen fuel cell system.
The battery was upgraded to lithium ion, from nickel-metal hydride, and total output from the electric motor increased to 134 kilowatts (180 hp), from 113 kilowatts (152 hp).
But demand for fuel cell vehicles is still constrained by a limited refueling infrastructure. Toyota estimates there are only about 160 hydrogen stations in Japan, 74 in the U.S. and 177 in Europe.
The overall market for passenger vehicles far outnumbers that of commercial vehicles. But Toyota now sees trucks as a key to jump-starting demand for fuel cells and to scaling up the refueling network. A larger network should help stimulate demand for passenger cars.
“The fact is,” Maeda said, “demand is generated more by trucks than by passenger cars because of fixed routes and therefore fewer stations, and this may lead to hydrogen acceleration.”